The invention relates to check valves and, in particular, to a diaphragm-type of check valve for venting an enclosed space.
Housings of various structures and systems may require venting of their interior to the surrounding atmosphere to prevent excessive build-up of internal fluid pressure. Such housings include control valve bodies having chambers that are intended to remain free of hydraulic fluid for proper control action and in which provision must be made for venting any leakage into the chamber to prevent control failure by development of a hydraulic lock. Other frequently encountered applications of such vent check valves include otherwise sealed mechanical transmission or pump housings in which excess heat may cause expansion of a gas or a liquid lubricant, creating undesirable internal pressure on the seals of the housing. In these and similar cases, a venting path is fitted with a check or one-way valve to prevent entry of contaminants and moisture into the housing.
One type of check valve, like the present invention, employs a resilient diaphragm as a single moving valve element. Examples of check or relief valves employing diaphragms are shown in U.S. Pat. Nos. 3,228,418 to Rosback et al. 3,519,012 to Van Patten, and 3,807,445, to McPhee.